package com.young.security;

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import org.springframework.web.servlet.view.freemarker.FreeMarkerConfig;

public class DEsApps {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
	    String content = "test";  
	    String password = "12345678";  
	    //加密   
	    System.out.println("加密前：" + content);  
	    byte[] encryptResult = encrypt(content, password);  
	    String encryptResultStr = parseByte2HexStr(encryptResult);  
	    System.out.println("加密后：" + encryptResultStr);  
	    //解密   
	    byte[] decryptFrom = parseHexStr2Byte(encryptResultStr);  
	    byte[] decryptResult = decrypt(decryptFrom,password);  
	    System.out.println("解密后：" + new String(decryptResult));  
	}
	
	/**将二进制转换成16进制 
	 * @param buf 
	 * @return 
	 */  
	public static String parseByte2HexStr(byte buf[]) {  
	        StringBuffer sb = new StringBuffer();  
	        for (int i = 0; i < buf.length; i++) {  
	                String hex = Integer.toHexString(buf[i] & 0xFF);  
	                if (hex.length() == 1) {  
	                        hex = '0' + hex;  
	                }  
	                sb.append(hex.toUpperCase());  
	        }  
	        return sb.toString();  
	} 
    /**将16进制转换为二进制 
     * @param hexStr 
     * @return 
     */  
    public static byte[] parseHexStr2Byte(String hexStr) {  
            if (hexStr.length() < 1)  
                    return null;  
            byte[] result = new byte[hexStr.length()/2];  
            for (int i = 0;i< hexStr.length()/2; i++) {  
                    int high = Integer.parseInt(hexStr.substring(i*2, i*2+1), 16);  
                    int low = Integer.parseInt(hexStr.substring(i*2+1, i*2+2), 16);  
                    result[i] = (byte) (high * 16 + low);  
            }  
            return result;  
    }  
    /** 
     * 加密 
     *  
     * @param content 需要加密的内容 
     * @param password  加密密码 
     * @return 
     */  
    public static byte[] encrypt(String content, String password) {  
            try {             
                    KeyGenerator kgen = KeyGenerator.getInstance("AES");  
                    kgen.init(128, new SecureRandom(password.getBytes()));  
                    SecretKey secretKey = kgen.generateKey();  
                    byte[] enCodeFormat = secretKey.getEncoded();  
                    SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");  
                    Cipher cipher = Cipher.getInstance("AES");// 创建密码器   
                    byte[] byteContent = content.getBytes("utf-8");  
                    cipher.init(Cipher.ENCRYPT_MODE, key);// 初始化   
                    byte[] result = cipher.doFinal(byteContent);  
                    return result; // 加密   
            } catch (NoSuchAlgorithmException e) {  
                    e.printStackTrace();  
            } catch (NoSuchPaddingException e) {  
                    e.printStackTrace();  
            } catch (InvalidKeyException e) {  
                    e.printStackTrace();  
            } catch (UnsupportedEncodingException e) {  
                    e.printStackTrace();  
            } catch (IllegalBlockSizeException e) {  
                    e.printStackTrace();  
            } catch (BadPaddingException e) {  
                    e.printStackTrace();  
            }  
            return null;  
    }  
    
    /**解密 
     * @param content  待解密内容 
     * @param password 解密密钥 
     * @return 
     */  
    public static byte[] decrypt(byte[] content, String password) {  
            try {  
                     KeyGenerator kgen = KeyGenerator.getInstance("AES");  
                     kgen.init(128, new SecureRandom(password.getBytes()));  
                     SecretKey secretKey = kgen.generateKey();  
                     byte[] enCodeFormat = secretKey.getEncoded();  
                     SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");              
                     Cipher cipher = Cipher.getInstance("AES");// 创建密码器   
                    cipher.init(Cipher.DECRYPT_MODE, key);// 初始化   
                    byte[] result = cipher.doFinal(content);  
                    return result; // 加密   
            } catch (NoSuchAlgorithmException e) {  
                    e.printStackTrace();  
            } catch (NoSuchPaddingException e) {  
                    e.printStackTrace();  
            } catch (InvalidKeyException e) {  
                    e.printStackTrace();  
            } catch (IllegalBlockSizeException e) {  
                    e.printStackTrace();  
            } catch (BadPaddingException e) {  
                    e.printStackTrace();  
            }  
            return null;  
    }  
}
